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# Component Guide

## AsyncAutoExposure

`AsyncAutoExposure` is the core runtime component.

Use it when you want to process any `Texture` manually from code.

```csharp
var exposure = gameObject.AddComponent<AsyncAutoExposure>();
RenderTexture corrected = exposure.ProcessTexture(sourceTexture);
```

### Inspector Fields

| Field                | Range            |     Default | Description                                                                                                        |
| -------------------- | ---------------- | ----------: | ------------------------------------------------------------------------------------------------------------------ |
| Auto Exposure Shader | Any `Shader`     | Auto-loaded | Leave empty to load `Resources/Shaders/AutoExposure`. Assign manually only for a custom luminance/exposure shader. |
| Target Brightness    | `0.1` to `1.0`   |       `0.4` | Average output brightness the plugin aims for.                                                                     |
| Adjustment Speed     | `0.1` to `5.0`   |       `4.0` | How quickly current exposure eases toward target exposure.                                                         |
| Min Exposure         | `0.3` to `2.0`   |       `0.5` | Lowest allowed exposure multiplier.                                                                                |
| Max Exposure         | `0.5` to `100.0` |       `3.0` | Highest allowed exposure multiplier.                                                                               |
| Downsample Factor    | `1+`             |         `4` | Divides the analysis resolution. Higher values are faster and less precise.                                        |
| Readback Frame Skip  | `0` to `10`      |         `2` | Frames skipped between brightness readbacks.                                                                       |

### Inspector Presets

The custom Inspector includes quick presets:

| Preset           | Use                                                      |
| ---------------- | -------------------------------------------------------- |
| Low Light        | Dark sources that need more lift                         |
| Balanced         | General webcam/video default                             |
| Bright Source    | Bright inputs that should not be over-amplified          |
| High Performance | Larger downsample and lower readback frequency           |
| High Quality     | Smaller downsample and more frequent readback            |
| Reset            | Restore package defaults and reset exposure in Play Mode |

### Runtime Monitor

In Play Mode, the Inspector shows:

* Measured brightness
* Applied exposure and target exposure
* Output texture size

## AutoExposureRawImage

`AutoExposureRawImage` processes a Unity UI `RawImage`.

Use it for:

* Webcam previews
* Video render textures
* Runtime camera feeds
* UI panels displaying a texture

Important fields:

| Field                  |      Default | Description                                                                                     |
| ---------------------- | -----------: | ----------------------------------------------------------------------------------------------- |
| Auto Exposure          | Auto-created | Reference to an `AsyncAutoExposure` component. If empty, one is created on the same GameObject. |
| Enable Auto Exposure   |       `true` | Main toggle.                                                                                    |
| Consider Alpha Channel |       `true` | Transparent pixels can be ignored during analysis.                                              |
| Continuous Update      |      `false` | Enable for live sources.                                                                        |
| Alpha Threshold        |        `0.1` | Pixels below this alpha are ignored.                                                            |

### Behavior

* The original `RawImage.texture` is cached.
* The component processes the original texture, then assigns `autoExposure.OutputTexture` back to the `RawImage`.
* If an external script swaps the source texture, the component detects the change and refreshes.
* Alpha masking uses the bundled `AlphaExtract` shader when the texture format supports alpha.

### Public Methods

```csharp
void ForceUpdate();
void ResetToOriginal();
```

Use `ForceUpdate()` after changing settings on a static image. Use `ResetToOriginal()` when you want to restore the unprocessed source texture.

## AutoExposureImage

`AutoExposureImage` targets Unity UI `Image` components.

Use it when working with sprites rather than raw textures.

Unlike `AutoExposureRawImage`, it does not draw the corrected result back through the original `Image`. It processes the sprite texture and displays the result in an assigned `RawImage`.

Important fields:

| Field                  |      Default | Description                                                            |
| ---------------------- | -----------: | ---------------------------------------------------------------------- |
| Auto Exposure          | Auto-created | Reference to an `AsyncAutoExposure` component.                         |
| Enable Auto Exposure   |       `true` | Main toggle.                                                           |
| Consider Alpha Channel |       `true` | Opaque sprite pixels drive the brightness calculation.                 |
| Continuous Update      |      `false` | Keep disabled for static sprites unless the sprite changes repeatedly. |
| Alpha Threshold        |        `0.1` | Sprite pixels below this alpha are ignored.                            |
| Output Raw Image       |       `null` | Required display target for the corrected texture.                     |

### Public Methods

```csharp
void ForceUpdate();
float GetCurrentBrightness();
```

`GetCurrentBrightness()` performs a one-off brightness check using the current sprite texture. When alpha-aware metering is enabled, the sprite texture must be readable because the component extracts alpha values on the CPU.

## Choosing The Right Component

| Need                                               | Use                                           |
| -------------------------------------------------- | --------------------------------------------- |
| Process a webcam or video texture in custom code   | `AsyncAutoExposure`                           |
| Add correction to a `RawImage` without custom code | `AutoExposureRawImage`                        |
| Correct a sprite from a UI `Image`                 | `AutoExposureImage` plus an output `RawImage` |
| Meter only the subject or foreground               | `ProcessTextureWithMask()`                    |
| Meter only visible UI pixels                       | Enable `Consider Alpha Channel`               |


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